Studies of the renin-angiotensin aldosterone system will be continued: 1) Dose-response relation of angiotensin II (AII) will be determined for blood pressure change in hibernators. 2) Determination of the aldosterone response of hibernators to ACTH and AII. 3) The effects of 1-sarcosine-8-alanine AII will be determined during a bout of hibernation. We also plan to follow blood pressure, cardiac output and peripheral resistance over an entire bout of hibernation including induction to and arousal from hibernation. Glucose Tm will be also measured in chronically catheterized animals.